There are widely known “3-piece type” disposable diapers that absorb excreted fluids such as urine.
Such 3-piece type disposable diapers are generally provided with a crotch section sheet member that is long in one direction and covers the crotch of the wearer, an belly side sheet member covering the belly side of the wearer, that is connected to one edge side of the lengthwise direction of the crotch section sheet, and a back side sheet member covering the back side of the wearer, that is connected to the other edge side in the lengthwise direction of the crotch section sheet member. The crotch section sheet member, the belly side sheet member and the back side sheet member usually have their joint sections bonded together by an adhesive at the sections where they overlap.
Incidentally, when excreted fluid such as urine has been excreted by the wearer of a disposable diaper, the excreted fluid is absorbed and held by an absorbent body provided in the crotch section sheet member, and therefore the absorbent body draws in excreted fluid each time it is excreted and gradually becomes heavier.
During this time, the weight of the absorbent body increases the overall weight and acts as downward force on the crotch section sheet member to which the absorbent body is attached, such that the crotch section sheet member is pulled downward at the joint sections between the crotch section sheet member and the belly side sheet member or the crotch section sheet member and the back side sheet member.
When this occurs, and there are no measures designed to deal with it, the tensile force accompanying the weight of the absorbent body causes separation and sagging of the crotch section sheet member from the joint sections with the belly side sheet member and/or back side sheet member, potentially damaging the disposable diaper.
Consequently, as described in PTL 1 for example, reinforcing members are provided to reinforce bonding at the sections where the crotch section sheet member overlaps with the belly side sheet member and back side sheet member, so that even when the crotch section sheet member is pulled downward by weight, separation of the crotch section sheet from the belly side sheet member and back side sheet member is prevented.
However, while damage to the disposable diaper is avoided by providing such reinforcing members, the reinforcing member-attached sections become more rigid, causing the sheet members to become hard and stiff, and significantly lowering comfort when worn. Furthermore, since air permeability of the sheet members is inhibited at the sections where the reinforcing members are provided, this can increase unpleasantness for the wearer and has been a cause of reduced comfort.